Stan.Shaw@Excell.Net

Stroking a 5L to 6L will need additional flow from the heads and intake as well, correct?

So to get the performance capability of the 6L bottom end, the top end will still need work, right?

928SS

good prices on those rods and pistons greg!! I used the 6 counter weight moldex and balanced everything at the same time w/the pistons, rods, etc. didn't need much as I told moldex what I was using so they just built the crank accordingly. greg at precision has been using this formula for a while now and has been quietly cranking these out like hot cakes for SOCAL shark owners.

not that easy w/968 pistons. the 968 pistons are rather tall on the compression height, and will yield static comp. of 11.6:1 or so w/a 97mm stroke crank, " std"5.85" rods and average deck heights. so you'd either have to reduce the stroke, or use shorter/custom length rods... been a lot of talk about that dilemma on this board over the years. that's part of the reason I went w/custom JE's w/968 flycuts and a lower CH. I also don't trust the mahle coating thing after pulling out my pistons and seeing how scuffed up they were. imo, nicom is much more durable and w/AL pistons it's proven technology w/nascar, lots of other motors.

stan - I don't think any serious engine builder would even consider increasing displacement w/out increasing valves, ports, exhaust, etc to keep up w/the flow. even w/all that I know I could get another 140rwhp if I used a CF or ITB intake system cause it's pretty restricted to about 450-500chp or so w/the stock intake system. but I think you already knew that

brendan - took apart the new car already??
U R da man!

Stan.Shaw@Excell.Net

Hi Rob,

I wasn't sure if I was missing something. I thought some here might be thinking that a $5k stroker shortblock would be equivalent to an SC setup.

heinrich

Greg I have a number of S4; S32 and GTS and 968 items. So I am very interested in this effort. I do already have the crank though.

tv

From a previous thread:

"GREG_If somebody could post them, my spreadsheet that is, I will email you my headflow figures for my 2 valve Euro, it will flow just under 600 hp with the cams I have. The spreadsheet is in excel format. It is quite clear but this is the best I could scan. "

Don't know the poster, but it seems to have enough capacity. Greg has done his valve work though. I have been paying attention to this stuff with the thought one day of making a reallly hot n/a euro engine.

Stan.Shaw@Excell.Net

TV,

My only question is what work (expense) is required to make the heads flow well enough. I am presuming the comment you pulled does not refer to stock heads, right?

BC

Ah, Brian, I have resisted. I have pictures, but not of my own engine. I did do the exhaust though. And a cat bypass.

And because of the prices of things, I can buy a longblock to play with so there is no downtime.

Vilhuer

Isn't "stock" stroker crank 95.25 mm stroke? In any case I will most likely have custom rods made. There are semi finished chevy rods available locally which do not have upper hole drilled for example allowing minor adjustment by it's placement. Aim is to have compression somewhere between 10.5 and 11.0:1 with GT cams. Bore/sroke ration will not be best possible but rev limiter is going to be stock GTS or S4 anyway.

928SS

my bad. yep - 95.25mm is about as far as you can go w/out serious block clearancing work. been a while... sounds like fun

heinrich

Rob, so how does this info alter your calculation?

928SS

hey H mine is done/running, so it really doesn't do anything to my old gal. I used: http://kb-silvolite.com/index2.php to help w/compression calcs back in the day. I suppose if a thick enough head gasket is used, that might help keep compression down a bit too. I stuck close to OEM thickness on my head gaskets (.043") iirc, in order to keep quench undisturbed as much as possible. but I had JE hog out the pistons a bit more (around 35cc) than a std 968 (around 28cc, iirc) to help keep compression down w/a zero deck height and 5.85" cheby style rods. there's a few ways to skin the old cat, but keeping compression down enough for 92 octane CA street gas was probably the biggest challenge.

iirc, the cheby 7L motors have combustion chamber that 30% bigger than ours to keep compression down... since we cant' do much w/the heads, we're kinda stuck squeaking out extra space by bigger piston dishes or dropping the pistons down, larger head gaskets or sacraficing rod angle or stroke like V is planning.

cost calcs kinda depend on how much he got the 968 stuff for and the cost of custom rods, I'd guess... but the top end stuff/all the incidentials would remain. iirc, pauter does a nice custom rod in any length for around $1400.00 a set, and they use an offset bolt arrangement that eliminates the need for clearancing... iirc, olivers can also be used w/out any clearancing too - but I'm not sure about custom sizes w/them.

looks like greg's idea is pretty slick too. now if we could just find good builders that cost $20/hr instead of $100/hr and custom aftermarket heads for $1000/set, cams for $300/set complete (like cheby), we'd be in fat city!!

heinrich

Rob, I hope we get to hang out a bit at SF06 .... My goal is to drop the GTS crank into an S4 motor (I have a few here) and go on down the road. To do this with minimal cost/fuss, I was thinking GTS pistons. However it appears those pistons are not easy to find. So since I have the 968 pistons sitting here looking pretty I may just drop them onto the GTS crank and S4 rods and an S4 block. Boring will be the cheapest solution then. However I need to figure out if the 968 pistons and GTS pistons have the same deck height I guess.

928SS

sounds like trouble, fun, or fun trouble iirc, boring and cyl prep on alusil was about the same as boring and nicom, fwiw. I've seen piston specs here before, if you can't find'em I've got some notes here... someplace

Vilhuer

Be patient and you will find out. I'm quessing no as stroke is different, 85.9 mm in GTS and 88.0 mm in 968. Will measure both pistons styles among others one day soon hopefully.

tv

Stan, I think that was talk about stock LH euro heads that breathe very well. I believe Greg has done his work because he wanted lighter valves and new parts for the high rpm use and went bigger.